Hi all, I was just wondering whether there is a proper difference between a moon and a planet. The only answer I've been able to find is that moons orbit planets, and planets orbit stars. But in reality, planets and moons both orbit their common centre of mass. So to frame my question clearly, would it be a planet with a moon if they were the same mass? Would they both be planets, both be moons or what? Kind of a pedantic question perhaps, but I couldn't find a clear answer.